This invention relates generally to scanners, copiers, facsimile machines and other devices used for transforming an optical image of a document into a electronic signal and more specifically to a reflective surface used behind a document to be imaged.
Electronic document scanners, copiers, and facsimile machines transform an optical image of a document into an electric signal suitable for storing, displaying, printing or electronic transmission. Documents to be scanned may generally be classified as either transparent or opaque. For opaque documents, light is reflected off an image on the surface of the document onto a photosensitive transducer, typically a photoconductive drum or an array of photosensitive sensor elements. However, documents are rarely completely opaque. In a typical device, some light passes through the document to a secondary reflective surface, for example a lid or automatic document feeder. Some light then reflects off the secondary reflective surface and passes back through the document a second time. The light that passes through the document twice may also be detected by the photosensitive transducer. If the document has an image on both sides, the image adjacent to the secondary reflective surface may be partially imaged onto the photosensitive transducer. For example, when copying double sided documents, sometimes an image on the back of the document partially appears in the resulting copy. This undesirable result is often called xe2x80x9cbleed-through.xe2x80x9d There is a need for reduction of bleed-through in copiers, scanners, facsimile machines and similar devices.
FIG. 1 shows prior art scanner cover with a reflective surface 103a on the scanner cover 103f. The reflecting surface 103a is formed by evaporating silver, chrome or aluminum onto one side of a transparent polyester film 103b. To the reflecting surface 103a, a hard plate 103d of a hard plastic material is bonded. Further, the plate 103d is supported by scanner cover 103f of a hard plastic material having reinforcing legs 103e. One possible alternative is that a metal is evaporated to the plate 103d, or that the plate 103d is made of a metal.
FIG. 2 shows another prior art scanner cover and reflective surface, wherein the original cover 103 includes a covering 103f of a resin, an elastic member 103g, such as sponge, a hard plate 103d of a plastic material which is not easily deformed and a transparent polyester film 103b having a reflecting metal surface at one side thereof, which are overlaid in the order named. Since a hard plate 103d is sandwiched by the reflecting surface 103a and the resilient member 103g, the surface 103a is not deformed and can softly press the original when a three-dimensional original is placed thereunder. One alternative is that a metal is evaporated to the plate 103d, or that the plate 103d is made of metal.
FIG. 3 shows another prior art scanner cover and reflective surface, wherein the layer 103b of FIG. 1 is supported by a resin sheet 103h which is of transparent and flexible synthetic resin. Because of this, the possible shock or uncomfortable closed relatively strongly. In FIG. 3, the reflecting surface 103a is shown as being formed between the sheet 103b and the sheet 103h, but it can be between the sheet 103b and the sheet 103d. 
An improved document lid and secondary reflective surface is provided that minimizes bleed-through and other image parameters of interest, such as brightness, contrast and color shift. The document lid and secondary reflective surface also permits a cost and labor savings in the lid and permits the lid to be recycled.